Hey ya. Thanks for your reply.
Alright, so I do have a classic LDAP set up. Beside an admin user, all users are authenticating against LDAP. Also, I use two accounts - one is my private account and one for business use.
This works well as long as I am only looking at the web interface and not looking beyond one account at a time.
It starts to get interesting when I use the Android client. Adding both accounts I have two ways to identify the accounts:
- The full name - which is identical for both accounts
- The user name - which is the UUID LDAP provides as userId
Also, on the file system, I do have UUIDs instead of user names.
With newer version of the LDAP module I can define an LDAP attribute which I like to use as a user ID field. As I have a “username” field I have a pretty good idea which one I will use 
Now, I am not the only one using the installation. Many users have quite a few files in their storages plus use contacts and calendar.
Is there any way of transitioning?